INTECH   27907
Unidad Ejecutora - UE
congresos y reuniones científicas
Nitrogen metabolism is altered in arabidopsis plants with modified polyamine levels subjected to nitrogen deficiency
Congreso; XIV PABMB Congress- LV Annual Meeting of the Argentinean Society for Biochemistry and Molecular Biology Research; 2019
Institución organizadora:
Nitrogen (N) is one of the most important nutrients in plant growth and is a constituent of many stable compounds such as aminoacids, proteins and polyamines (PAs). In Arabidopsis thaliana, where the PA putrescine (Put) is produced exclusively through the arginine decarboxylase (ADC) pathway, two genes encode ADC (ADC1 and ADC2). The objective of this work was to study the interrelation between N and PAs metabolisms in Arabidopsis plants under N deprivation. Leaves of wild type plants (WT), a line defective in Put biosynthesis (adc1) and a line overexpressing ADC (7.2) were used. Plants were grown in a Hoagland basal nutrient media containing normal (C) or reduced (Low N) total nitrogen content, in hydroponics for 21 d. In C media, free Put content in adc1 and 7.2 lines was 35% lower and 2,5-fold higher, respectively, than in WT line, whereas in low N medium, Put content decreased close to 30% in WT and adc1 plants but did not change in 7.2. Spermine content was greatly increased in adc1 respect to WT plants in both media. The mutant adc1 has a slight higher fresh biomass and protein content in N7 medium, but seemed to be the more affected one when grown under N deprivation in terms of growth, protein or chlorophyll content and showed a different behavior in some aspects of N metabolism respect to WT, in basal and deficient media. Nitrate reductase activity was lower in adc1 line and slighlty changed in 7.2 line compared to WT in C medium, while in low N medium, its activity decayed in WT and adc1, but it maintained its level in 7.2. Ammonium and nitrate levels were reduced in low N respect to C in a comparable rate in all lines, but the decay was less pronounced in 7.2. The aminoacids glutamate, glutamine, arginine, proline and GABA were higher in C respect to low N media in the three studied lines. However, adc1 showed elevated levels of the five compounds respect to WT in C, but all compounds decreased in the mutant line compared to WT in low N media. In 7.2 line, only GABA and glutamate showed higher levels respect to the WT in C medium. Altogether, these results suggest that N depletion affected PAs or nitrogenated metabolites formation differently in WT, mutant or transgenic plants, highlighting the importance of N intermediates flux through the major network of nitrogen-metabolizing pathways in plants under N deficiency.